PITTSBURGH -- Dwight White, the Steel Curtain defensive end known as "Mad Dog" who helped lead the Pittsburgh Steelers to four Super Bowl titles in the 1970s, died Friday. He was 58.

The Steelers said White died at a Pittsburgh hospital. The cause was not disclosed. The team said White was released from the hospital after having back surgery, but then was readmitted with complications.

White is the second member of the original four-man Steel Curtain to die this year. Defensive tackle Ernie Holmes died Jan. 17 in a car accident in Texas.

White, a two-time Pro Bowl player, was chosen as one of the 33 members of the Steelers' 75th anniversary all-time team last season.

White was best known for climbing out of a hospital bed to play in the Steelers' first Super Bowl victory, 16-6 over the Minnesota Vikings in 1976. White lost 18 pounds after being diagnosed with pneumonia and a lung infection, yet played nearly the entire game.

White made three tackles for no yards as the Vikings ran seven of their first eight running plays his way and went on to finish with only 17 yards rushing on 21 attempts. White also accounted for the only points of the first half when he sacked Fran Tarkenton in the end zone for a safety.

White, a former player at East Texas State (now Texas A&M-Commerce), gained his nickname because of his intensity. He often said that playing on the defensive line was like having "a dog's life."

Steelers chairman Dan Rooney said that inner drive was the reason the 6-foot-4, 250-pounder could play so well only hours after being hospitalized.

"He played with a relentlessness that led us to four Super Bowl titles in the 1970s," Rooney said in a statement. "Dwight refused to be denied, as was evidenced when he walked out of the hospital with pneumonia to play in Super Bowl IX and had an outstanding game. Dwight will be remembered by those who knew him even more for being a wonderful and caring person."

Rooney's son, Steelers president Art Rooney II, said the organization "lost an important member."

"He always seemed to rise to the occasion when it counted most and added an element of toughness that was synonymous with our teams of the 1970s," Rooney II said.

White was a fourth-round draft pick in 1971 after being a first-team All-Lone Star Conference player and team captain at East Texas State as a senior.

White made his first Pro Bowl in 1972, playing on a Steelers defensive line that also featured Hall of Famer Mean Joe Greene and defensive end L.C. Greenwood.

White repeated as a Pro Bowl selection in 1973 and his 46 sacks from 1971-80 are the seventh most in Steelers history. He had 33 1/2 sacks from 1972-75, with three in the Steelers' 21-17 victory over the Dallas Cowboys in the January 1976 Super Bowl.

White was chosen by The Associated Press as a first team All-AFC player in 1973.

White retired after the 1980 season -- one of the first players from the Steelers' Super Bowl teams to do so -- and became a prominent stock broker in Pittsburgh and one of the most successful former Steelers in the business world.

Most recently, he was senior managing director of public finance for Mesirow Financial in Pittsburgh. Before that, he was a partner and principal operator of the Pittsburgh office of W.R. Lazard & Co., plus a company board member, and worked for investment firms Balche-Halsey and Daniels & Bell.

"Let's just say, like Yogi Bear used to say, I'm smarter than the average bear," White told Pittsburgh author Jim O'Brien in 1991. In the same interview, he said his one vice was he smoked too much.

White, the oldest of three children who grew up in Hampton, Va., and Dallas, also was involved in numerous community events and charity activities.

"He had a special gift that enabled him to liven up any room that he entered," Rooney II said.

White also was chairman of the Pennsylvania Governor's Council on Physical Fitness and Sports.

"His NFL nickname, Mad Dog, belied the fact that he was a true gentleman and an accomplished business leader," Gov. Ed Rendell said in a statement. "After retiring from football, he entered the financial services industry with the same tenacity and determination he showed on the football field."